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J..R. C. AUGUST` MUFFLE FURNACE.

APPucmoN man mw 8.1920. 1,41 5 ,424. Patented May 9,1922. Eers- 2 SHSHEET I.

' v f fa@ Q5-@$2 www UNITED STATES PATENT orifice.

JOHANNES ROBERT CARL AUGUST, or HALIFAX, ENGLAND.

Application led'May 8,

To all whom t may concern: i

Be it known that I, JOHANNES ROBERT CARL AUGUST, subject of the King ofGreat Britain, residing in Halifax, in the county of York and Kingdom ofEngland,have invented certain new and useful Improvements in or Relatingto Muiile Furnaces, of which the following is a specification.

This invention has reference to rotary muiile furnaces of the type inwhich the muiiie or barrel is concentrically mounted and supportedwithin a rotary heating chamber or furnace so that while both revolvetogether spaces ,are left between them,` and in which the electricallyproduced heat is made use of to heat the muffle. y

The invention kwill be understood from the followingidescriptionreference being had to the accompanying drawings, in which Figure l is alongitudinal section of my furnace, and

Figure 2 is a similar view showing a modication. l

Referring to Figure l, the rotary furnace comprises a cylindrical metalcasing 20 lined inside with fire clay Slabs 2l, and extends in ahorizontal or slightly inclined direction,

and the barrel orvmuiiie 22 is supported con' cent'rically inside thecasing 20. At one end,

the rotary casing has a circular concentricr aperture 25, and the barrel22 which may be y made of fire clay is closed at ythe inner end, whileinside this barrel 22 and fairly `closely fitting it, is a movablecontainer 49 to receive the articles which are to lbe subjected to heattreatment. This container 49 which may be of metaljs inserted throughthe cen-- tral aperture 25 of the rotary casing 20, and

rthrough the open end ofthe barrel 22, and

the open end of this container is provided with a removable gas tightcover or closure 27. The outer end of the container which may beenlarged a little as shown,extends a little beyond the end of thecylindrical casing 20, and its cover may consist of a plate 27 securedby nuts and set pins tothe lianged outer end of the container 49, andmay carry on its inner side by meansof rods, an inner plate or diaphragm27X which abuts against. the shoulder at the junction between thecontainer proper and its enlarged end. By the removal of this cover, thearticles to be subjected to heat treatment, can be readily v intro ducedand afterwards withdrawn. The barrel 22 is xedly supported inside theMUFFLE FURNACE.- f

192,0. Serial No. 379,995.`

specication of Lette'rsratent. Patented May' 9,1922.

lic bands 3l cooperating with thek carrying rollers 30 resisttaryfurnace. The disposition of the parts enablesthe container 49'to bewithdrawn at anytime required without disturbing the outer casing 20 orthe barrel 22. The electric heater is shown at 4 l This consists of aheating coil ofkwire wound round the barrel 22 so as to be supportedthereby and designed to receive 'a current of electricity, and toproduce by resistance heating effects.` coils 46` are insulated fromtheouter casing 2O by a supplementary casing 22 of ireclay and y asurrounding casing of insulating material 50 such as asbestos, mineralwool or the like, both around the barrel 22 `and at the inner endthereof, that is to say in the annular space between the casing 2O andthe barrel 22, and in the space between the end of the barrel and thecasing. The insulating material 50 keeps the coil spaced apart withoutdanger of accidentaldisplacement. For supplying current to the electricheater 46 there-.is arranged upon the outside ofy the longitudinal playof the ro-u These heating and bearing against these contact ringsarebrushes (not shown) carried by suitable supports. The heater 46 isconnected through the wires 51` with the outer rings 48. Cooperatingwith these parts is a switch board which is connected to the source ofelectrical supply.

'The furnace shown in Figure 2 is similarto that described in Figure l,except that in Figure 2 the electric heater 47 consists of somesubstance in a powdered granulated or compound state capable ofproducing by resistance heating eects, as for instance ferifo-silicon,of suitable compositions and re Sistances. 20 as before is the outermetallic casing lined inside the fire clay slabs 2l, 22 the barrel orInutile supported concentrically, 25 the circular concentric aperture,49

the metal container, 27,27x the cover there- CII inder 52 is interposedin the annular space between the barrel 22 and the outer casing 2O so asto torni an. annular chamber between the barrel 22 and the said cylinder52, in which chamber the powdered material. 4:7 is packed, and anannular chamber between the barrel 22 and the outer easing 2() in whichchamber insulating` material 50 is inserted such as asbestos, mineralwool or the like, so as to insulate the heating unit 47 and the cylinder52 from the outer casing,` 20. The chamber in which the heating,` unitis placed, is completely closed on all sides, as will be noted from thedrawing by the cylindrical portion of 52 and the ends thereof and by thebarrel 22 so that the powdered material cannot escape, and the heat mustnecessarily be absorbed by the barrel 22. For supplying current to theheating` unit 17, there is arranged on the outerl casing 20' at the end,

contact rings 4:8 and bearing against these contact rings are brushes.The heating' unit -i-l-7 is connected through wires 51 with the outerrings i8, one of these wires supplying` current to the heating; unit andthe other beinn,` the return wire.

To operate the furnace, the articles to be carburized for the purposeol? ease hardening them, or be otherwiee subjected to heat treatment,are :introduced into the container 4.9, and the cover 27, 27X is closed.The current is turned on, the furnace set into rotation, and theheating` unit is cut into circuit` whereby the interior ot the containeris raised to the requisite temperature.

l declare that what l claim is:-

l. A rotary furnace ot the rotary barrel type, formed. by thecombination. ot a rotary chamber closed at one end. and having a centralaperture at the other, a inutile or barrel concentrically mounted insidethe said rotary chamber so that while both revolve together an annularspace is left between them, an electric heater located in the saidspace, and insulated from the said rotary chamber, and a removableeontainer inserted closed end irst into the barrel through the saidcentral aperture,` while the open end which is closed by a detachablecover is lett projecting.

2. A rotary furnace ot' the rotary barrel type formed by the combinationof a rotary chamber closed at one end, and having a central aperture atthe other, a muitle or barrel .concentrically mounted inside the saidrotary chamber so that while both will revolve together, an annularspace is left between them, a supplementary lire clay cylinderinterposed in the annular space between the barrel and the outer chamberso as to 'term an inner annular chamber between it and the barrel, andan outer annular chamber between it and the outer chamber, an electricheating; unit composed oi" powdered material inserted in the innerannular chamber and insulating material inserted. in the outer one.

3. A rotary furnace of the rotary barrel type, 'termed by thecombination ot a rotary chamber closed at one end and haring a centralaperture at the other end, a inutile or barrel concentrically mountedinside of the said rotary chamber so that while both revolve together7an annular space is lett between them, a heater located in said space,and a removable container inserted closed end first into the barrelthrough the aperture, and a removable cover closingthe open end oil" thecontainer.

4l. A rotary furnace ot the rotary barrel type, toi-.ined ot a rotarychamber closed at one end and ha ring a central apei'ture at the otherend, a removable container inserted closed end first into the aperture,an electric heater si1rroundingthe container, and a detachable coverclosing;l the open end oi the coi'itainer.

ln witness whereof, l have hereunto signed my name this l9th day ofApril, 1920, in the presence ot two subscribing witnesses.

JGHANNES ROBERT CARL AUGUST,

llitnesses AUGUSTUS E. INGRAM, l. E. Nici-rotte.

